There are very few nights that are unforgettable and extraordinary occasions which go down in a football club’s history.

This was without question one of them after a barmy evening in East London which ended with the entire team, coaching staff and chairman Barry Hearn celebrating from the directors’ box in front of the fans.

Thousands of Orient supporters saluted their heroes as a mass pitch invasion erupted at a sold-out Brisbane Road. It felt like the O’s had already won promotion but you could understand just what this meant to a club that has been written off time and again.

There is still a job to be done at Wembley Stadium on Sunday, May 25 against either Preston North End or Rotherham United but it would be foolish to bet against Russell Slade’s side after this phenomenal season.

I have been to play-off finals, the League Cup final and European Championship matches over the last two decades as both a fan and a reporter but I’m struggling to think of a game which generated a better atmosphere.

From the kick-off, there was an incredible noise from all sides of the capacity crowd and it just did not stop throughout the tie. This compact, little ground has probably never heard anything like it before but it truly was an incredible experience as fans poured onto the pitch once Orient’s place at Wembley was confirmed.

The O’s were favourites to progress after earning a 1-1 draw in the opening leg on Saturday but for the first hour of this contest, there was very little to separate the sides.

The first half lacked the excitement of the first game, with very few openings for either side, but the deafening noise bellowing around the Matchroom Stadium more than made up for this.

Lloyd James went closest but the midfielder’s long-range strike was palmed round the post by Posh keeper Bobbt Olejnik.

Peterborough almost claimed the lead in the second period when full-back Mark Little raced in on goal but his low shot struck the outside of the post.

This was a costly miss as Orient went in front on aggregate, for the first time, after 60 minutes.

Dean Cox’s free-kick from just outside the area was blocked but the ball rebounded to the winger and he struck a fierce low volley into the corner of the net. This sparked absolute pandemonium as Cox raced to the corner of the pitch where he was buried beneath bodies of ecstatic fans and teammates.

After this breakthrough, you expected a response from Peterborough but it never really materialised and Orient looked more likely to go on and add to their lead.

Shaun Batt made an impact from off the bench on Saturday and the super sub was at it again on Tuesday when he made another hugely significant contribution.

David Mooney fed the former Posh forward and Batt showed exceptional pace as he raced down the wing before cutting the ball back for substitute Chris Dagnall to smash his effort into the net.

This felt like the moment Orient had clinched their place in the League 1 final but the O’s know how to string out the drama.

United had five minutes of injury time to produce something miraculous and they gave themselves a lifeline when Conor Washington fired in a shot which sent keeper Jamie Jones the wrong way.

Peterborough threw every single player, including Olejnik, forward for the final seconds in search of an equaliser but Orient survived and the players were quickly engulfed by a sea of red.

Watching Slade and his players celebrate from up high in the box felt like a truly surreal yet brilliant experience. It was one they deserved to savour but the hope is similar scenes in North London will be dominating this website in less than a fortnight’s time.